There are currently two formats associated with standard HDTV (High Definition TV). These two formats are the 720p format and the 1080i format. The 720p format produces progressive pictures comprising 720 lines and 1280 columns and the 1080i format produces interlaced pictures comprising 1080 lines and 1920 columns. Each of these formats has advantages that are specific to it. The 720p format presents a better temporal resolution and reproduces fast moving objects without creating a blur effect while the 1080i format presents a better spatial resolution. The programme broadcasters have chosen to use one or other of these formats but not both together. There is therefore a real necessity to process, prior to display, the format of broadcast programmes, to transform it into a format supported by the display device used to display said programmes.
It is known in the art to change the format of a video picture by first carrying out a detection of the local edge orientation in the input picture then carrying out an interpolation based on the detected orientations. A distance representative of the edge orientation is calculated at a point of the input picture having the same spatial position (i.e. the same spatial coordinates) as the pixel of the output picture to be interpolated and this distance is then used to calculate the value of this pixel of the output picture. This method is relatively complex and consuming in terms of calculation resources.